The invention relates to an electric device such as an electric vehicle of an electric bicycle, an electric wheelchair, or the like using electric energy by a battery as a power supply and a method for charging and discharging a battery unit of the electric device.
There is an electric vehicle such as an electric bicycle or an electric wheelchair on which a storage battery pack composed of a plurality of storage batteries is mounted as a power supply. The vehicles of this type include one running only on a driving force of a motor driven by electric energy (electric power) from the mounted storage battery pack, one running on the resultant force of a driving force of a motor and human power, one selectively using a driving force of a gasoline engine and a driving force of a motor, and the like.
The storage battery mounted on these vehicles as a power supply needs to be frequently charged, and there are methods for charging it, that is, a simplex charging method of charging the battery detached from the vehicle and a mounted-on-vehicle charging method of charging the battery mounted on a vehicle.
For example, a storage battery of a large capacity with a heavy weight, as compared to the weight of a vehicle main body, may need to be mounted on an electric device such as an electric vehicle. In this case, it is difficult to detach and carry the storage battery by hand because of the heavy weight thereof. For this reason, the vehicle, an electric device, is provided with a charging apparatus, and the vehicle is moved and near a commercial power supply. Meanwhile, in the case of a storage battery mounted on the vehicle with a relatively light weight, one charge method is detaching the storage battery from the vehicle and connecting it to a charging apparatus, which is separately positioned.
A conventional electric device using a storage battery pack as the storage battery and a method for charging the storage battery pack are explained here using FIG. 15 to FIG. 20B.
FIG. 15 to FIG. 17 show examples of an electric device on which a battery section and a charging apparatus therefor are fixedly mounted. Each of electric devices 200, 210 and 220 is composed of a charging apparatus 201, a battery section 202, a controlling apparatus 203, and a driving apparatus 204, which are connected in parallel, and a motor 205, which is driven by the driving apparatus to drive a running section such as wheels.
In each of these electric devices, electric power from battery section 202 is supplied to the driving apparatus 204 to drive the motor 205, whose motive power drives the running section, such as wheels. The controlling apparatus 203 controls action of the driving apparatus 204.
The electric device 200 shown in FIG. 15, on which a set of storage battery pack 202a composed of, for example, a lead storage battery is mounted as the battery section 202, is often used for an electric wheelchair, an electric scooter, or the like. The weight of the battery section 202 in the case of the storage battery pack 202a, composed of the lead storage battery is as heavy as about 30 kg to 60 kg.
On the electric device 210 shown in FIG. 16, plural sets of storage battery packs 202a are mounted as the battery section 202, which can be constituted by connecting in parallel m rows of storage battery packs 202a each of which is constituted by connecting n single storage batteries in series.
The electric device 220 shown in FIG. 17 has thereon a plurality of (m pieces) storage battery pack units 202b connected in parallel as the battery section 202, in which each storage battery pack unit 202b is constituted by connecting n single storage batteries in series.
These electric devices 210 and 220 are heavily used for an electric vehicle operated for a long time, an electric device for moving an object having a large weight, an electric fork lift or an electric carrier vehicle requiring a large capacity or a power supply of bulk power. These devices often have a battery section 202 having a weight of more than about 60 kg.
Since each of the electric devices 200, 210 and 220 has thereon the battery section 202 and the charging apparatus 201 for charging it, charging is performed for the storage battery pack or packs 202a or the storage battery pack units 202b of the battery section 202 by moving or transporting the electric device together with the vehicle near a commercial power supply 100, connecting the commercial power supply 100 to the charging apparatus 201, and supplying a charging current to the battery section 202 by the charging apparatus 201. Alternatively, the battery section 202 can be detached from the vehicle and charged by a special apparatus.
It should be noted that in the electric devices 210 and 220 shown in FIG. 16 and FIG. 17, it is also possible to charge and discharge a plurality of storage battery packs 202a or storage battery pack units 202b as a unit, each constituting the battery section 202.
On the other hand, electric devices 300,310 and 320 shown in FIGS. 18A, 19A and 20A have no charging apparatuses thereon, and charging apparatuses 301 respectively shown in FIGS. 18B, 19B and 20B are provided in a garage or at a rest area. Each battery section 302 in FIG. 18, FIG. 19A or FIG. 20A is composed of storage battery packs 302a or storage battery pack units 302b, as in the battery section 202 in FIG. 15, FIG. 16 or FIG. 17, but is a unit attachable/detachable to/from the main body of the electric device 300, 310 or 320 and provided with connectors 306a and 306b for establishing electrical connection to the main body. The other structures are the same as in the electric devices shown in FIG. 15 to FIG. 17.
When charging is performed for the battery section 302 detachably mounted on the electric device 300, 310 or 320, the charging is performed by detaching the battery section 302 from the device main body and moving and installing it in the charging apparatus 301, which is separately placed and connected to the commercial power supply 100, as shown in FIG. 18B, FIG. 19B or FIG. 20B.
As the storage battery packs 302a or the storage battery pack units 302b of the battery section 302, for example, a nickel-cadmium (Nixe2x80x94Cd) battery having a relatively light weight of about 1.8 kg to 3.5 kg is used and mounted on an electrically assisted bicycle or the like.
When a not-so-large battery capacity and supply power of the battery section are required, as in the electrically assisted bicycle, the battery section is of a weight easily portable by human power, and thus it is easy to detach the battery section from the vehicle for charging.
However, the battery section of a typical electric device is inconvenient because it has a considerably heavy weight. Charging should be performed by moving the electric device (vehicle) itself to a place having a chargeable power supply, such as the commercial power supply or the like, or by transporting the battery section using a transporter to a place where a charging apparatus is provided.
Further, since only one of (one set of) battery section 202 or 302 is mounted on the above-described electric device, when the battery section becomes unusable because the storage state of its storage battery packs fall below a predetermined specified value (which is decided in accordance with specifications of the battery, requirements for the electric device, and the like), the electric device itself becomes unusable, even if the controlling apparatus, the driving apparatus, and the like, except the battery section, are usable. Thus, if the battery section is detachable, the battery section which becomes unusable should be exchanged for another battery section for powering the electric device.
Alternatively, it is necessary to charge the battery section, which has become unusable because the storage state of its storage battery pack falling below the specified value. In this case, there is an additional problem that it takes a long time to charge the battery section enough to make the electric device usable, unless a charging apparatus having a capacity large enough is used.
Furthermore, as for the battery section, when the battery section is constituted by connecting in parallel a plurality of storage battery packs or storage battery pack units as in the above-described electric device shown in FIG. 16 and FIG. 17 or FIG. 19A and FIG. 20A, it is necessary to limit the variation in the charge amount to within an allowable range or to provide means for controlling it so as not to cause the variation among the storage battery packs or the storage battery pack units.
Especially when a nickel-cadmium (Nixe2x80x94Cd) battery, a nickel metal hydride (Ni-MH) battery, or the like is used for the battery section, a so-called memory effect occurs such that the capacity of the battery decreases due to the use of the battery while charging and discharging are repeated with the discharge depth being shallow, and thus means for preventing this is necessary.
Further, when regenerative electric power from a load side, such as a motor or the like, is recovered for the battery section, charging often becomes impossible, depending on the state of the battery section or the degree of discharge, which prevents the regenerative electric power from being stored efficiently.
Therefore, a method of supplying power for an electric vehicle and an apparatus therefor are proposed which are configured such that storage battery packs each having a required capacity are mounted in a divided form in accordance with characteristics of an electric vehicle, and the storage battery packs are made connectable in series or in parallel to be charged or discharged singly or in combination as required, thereby improving the radiation property of the heat from the storage battery packs during charge and discharge to reduce the deterioration caused by heat so as to prolong storage battery pack life, and further the remaining capacities and the charge states of the storage battery packs can be recognized easily (See JP, 9-298805, A)
In this electric vehicle, the storage battery packs are connected in parallel to produce a large current when its load is large at the time of starting, accelerating, or the like, and a single or a plurality of the storage battery packs as required discharge a small current when its load becomes smaller at the time of traveling at a constant speed after the start, or the like.
The plurality of the storage battery packs are mounted and fixed on the vehicle in a manner not to contact each other.
Further, the management of the storage battery packs in this electric vehicle is conducted based on the use of the storage battery packs in a fully charged state and by a method of discharging one of the plurality of the storage battery packs and, after the charge the storage battery pack depletes, discharging the next storage battery pack.
As described above, this electric vehicle is configured such that the plurality of the storage battery packs discharge on a one-set basis and the remaining capacities of the remaining storage battery packs can be displayed when the above discharge ends, to enable easy recognition of the remaining capacities of the storage battery packs in the whole device. In the case of charging the storage battery packs, control of the device is conducted so that the charge is performed in a reverse order to that of the discharge. In other words, charge needs to be performed to be a full charge without fail.
However, since the plurality of the storage battery packs connected in parallel discharge respectively when a large current discharge is required because of a large load at the time of starting, accelerating, or the like, and a single or a plurality of the storage battery packs as required discharge a small current at the time of a light load such as at traveling at a constant speed, it is difficult to appropriately manage the remaining capacities of the storage battery packs, which presents the problem that it is impossible to conduct control for the most efficient charge and discharge.
Especially when using the storage battery packs in which a so-called memory effect occurs that the capacity of the battery decreases due to the use of it while charge and discharge are repeated with the discharge depth being shallow, it is desirable to conduct an optimal charge and discharge control for individual storage battery packs to prevent the memory effect, but such control is difficult.
Further, when the storage battery packs, which have ended discharge to the specified remaining capacities, are detached from the vehicle and charged by a charging apparatus at another place, it is impossible to check the charge and discharge states thereof with the storage battery packs detached and then conduct an optimal control because of the batteries being under standardized sequential management.
It is an object of the invention to solve the above-described problems in the conventional electric device and to enable an appropriate management and an efficient use, all the time, of a battery section provided with storage battery packs. More specifically, matters listed in the following are its objects.
(1) To facilitate detachment and carrying of the battery section by hand to eliminate the need to move the electric device at the time of charging and to eliminate the need for a special carrier for transporting the battery section.
(2) To improve usage of the battery section in the electric device for ease of use.
(3) To make it possible to perform operation and charge of the electric device in parallel without need for a special charging apparatus.
(4) To make it possible to manage battery characteristics of the battery section and freely select charge and discharge in accordance with the battery characteristics.
(5). To prevent a so-called memory effect when a secondary battery (storage battery), such as a Nixe2x80x94Cd battery, in which the memory effect occurs is used as the battery section of the electric device and to eliminate the need for refresh thereof.
(6) To improve detection accuracy of charge and discharge states of the individual storage battery packs in the plurality of the battery sections.
(7) To prolong storage battery pack life.
(8) To make it possible to use even different types of storage battery packs in combination.
(9) To facilitate charge by placing the charging apparatus at a battery station and to make it possible to recognize the charge and discharge states of the battery section at a high accuracy, even when it is detached from the electric device so as to enable an optimal charge control.
Further, to recover the regenerative electric power from a load side such as a motor or the like to the battery section so as to utilize it efficiently.
To achieve the above-described objects, the invention provides an electric device and a charging apparatus for charging a battery unit thereof, and a method for charging and discharging the battery unit as follows.
The electric device according to the invention comprises: a plurality of battery units detachably mounted thereon, each battery unit constituted by pairing a storage battery pack with a memory for storing at least information about charge and discharge states of the storage battery pack; and connectors provided on each battery unit and a battery unit installation section on a device main body side, for performing electrical connection/disconnection to/from the device main body side incident to attachment/detachment of the battery unit.
Additionally, a driver for driving a load, a charger for charging the storage battery pack by referring to the information stored in the memory of each mounted battery unit, and a controller for controlling the supply of electric power from each battery unit to the driver by referring to the information stored in the memory of each mounted battery unit, which are provided on the device main body side, and the charger includes means for reading at least the information about charge and discharge states of the storage battery pack stored in the memory of each battery unit, and means for writing into the memory at least the information about charge and discharge states of the storage battery pack in the same unit.
Here, the storage battery pack includes various types of secondary batteries such as a nickel-cadmium battery and a nickel metal hydride battery. The memory is a nonvolatile memory such as an EEPROM, a flush ROM, a RAM backed up by a battery, or the like, into which various kinds of information are written which include at least the information about charge and discharge states of the storage battery pack by the charger or the controller provided in the battery unit or on the electric device main body side. In addition, the information of the type and characteristics of the storage battery pack can also be written into them in advance.
As for this battery unit, the charge and discharge states of the storage battery pack included therein can be recognized precisely by referring to the information stored in its memory, even when it is mounted on the electric device or it is detached therefrom to be in a single state, and thus an appropriate charge and discharge control can be conducted all the time.
The electric device may comprise: a plurality of battery units detachably mounted thereon, each battery unit constituted by integrating a storage battery pack, a memory for storing at least information about charge and discharge states of the storage battery pack, and a charger for charging the storage battery pack; connectors provided on each battery unit and a battery unit installation section on a device main body side, for performing electrical connection/disconnection to/from the device main body side incident to attachment/detachment of the battery unit; and a driver for driving a load and a controller for controlling supply of electric power from each battery unit to the driver by referring to the information stored in the memory of each mounted battery unit, which are provided on the device main body side.
In this case, the charger of each battery unit has means for deciding a charge order by mutually referring to the information stored in the memory of each mounted battery unit.
Further the electric device may comprise: a plurality of battery units detachably mounted thereon, each battery unit constituted by pairing a storage battery pack with a memory for storing at least information about charge and discharge states of the storage battery pack, and provided with a switch connected to the storage battery pack in series; connectors provided on each battery unit and a battery unit installation section on a device main body side, for performing electrical connection/disconnection to/from the device main body side incident to attachment/detachment of the battery unit; and a driver for driving a load, a charger for charging the storage battery pack through the switch by referring to the information stored in the memory of each mounted battery unit, and a controller for controlling supply of electric power from the storage battery pack to the driver through the switch of the battery unit by referring to the information stored in the memory of each mounted battery unit, which are provided on the device main body side, and the charger may include means for reading at least the information about charge and discharge states of the storage battery pack stored in the memory of each battery unit, and means for writing into the memory at least the information about charge and discharge states of the storage battery pack in the same unit.
With these electric devices, a plurality of battery units can be detachably mounted thereon, and one or more battery units suitable for discharge can be selected based on the information about charge and discharge states of the storage battery packs stored in the memories provided in the battery units to allow them to discharge so as to supply electric power to the driving section.
Also in the case of charging the storage battery packs of the battery units, the charge can be selectively performed, while an optimal control is being conducted, for a single or a plurality of battery units by the charging apparatus provided on the device main body side, the charging apparatus provided in each battery unit, or the charging apparatus provided at a charger station based on the information about charge and discharge states of the storage battery packs stored in the storage apparatus in the battery units.
In these electric devices, the charger which is provided separately from the aforementioned battery unit can also be structured to be a unit attachable/detachable to/from the electric device main body, so that the charger (charger unit) can be detached, together with one or more battery units, from the electric device to charge the storage battery packs of the battery units.
Furthermore, it is desirable that the controller has means for reading the information about charge and discharge states of the storage battery pack stored in the memory of each battery unit and holding it therein, and means for controlling action of the whole device based on the information stored in the former means.
Moreover, it is possible that the memory of each battery unit also stores information about characteristics of the storage battery pack, and the charger has means for controlling charge of the storage battery pack, by referring to the information about the characteristics of the storage battery pack stored in the memory of each battery unit, in accordance with the characteristics.
Further, it is suitable that the controller has means for controlling discharge from the storage battery pack, by referring to the information about the characteristics of the storage battery pack stored in the memory of each battery unit, in accordance with the characteristics.
Further, in these electric devices, the controller desirably has means for displaying a remaining capacity of the storage battery pack of each battery unit based on the information stored each battery unit, and displaying a charge request and/or giving an alarm when a storage battery pack needing to be charged exists.
A method for charging and discharging the battery unit in the electric device according to the invention comprises the steps of discharging in order the storage battery packs of the battery units mounted on the electric device to a predetermined remaining capacity and then charging them, by referring to the information stored in the memories respectively.
Alternatively, it is preferable to discharge the storage battery packs of the battery units mounted on the electric device in decreasing order of remaining capacity, and to charge them in increasing order of remaining capacity, by referring to the information stored in the memories respectively.
Further, it is also preferable to discharge the storage battery packs of the battery units mounted on the electric device in increasing order of remaining capacity, and to charge them when the remaining capacities become a predetermined value or less, by referring to the information stored in the memories respectively.
Furthermore, it is also preferable to select one or more of battery units mounted on the electic device an discharge storage battery packs thereof, and to select remaining one or more battery units and charge storage battery packs thereof, by referring to the information stored in the memories respectively.